Composition for obtaining foamed polyvinylchloride material and method of obtaining it

ABSTRACT

PCT No. PCT/RU93/00177 Sec. 371 Date Apr. 3, 1995 Sec. 102(e) Date Apr. 3, 1995 PCT Filed Jul. 26, 1993 PCT Pub. No. WO94/04602 PCT Pub. Date Mar. 3, 1994A foamed polyvinylchloride (PVC) material is produced by mixing of 100 mass parts of PVC with 0.5-5 mass parts of sodium alkyl sulfonate, molding of the obtained composition and followed by heating for foaming at 190 DEG -300 DEG  C. for 3-20 mins. Molding is performed either under 0.5-400 MPa and 20 DEG -170 DEG  C., followed by heating to 140 DEG -150 DEG  C. in the closed space, or in a free state in the form of 2-16 mm thickness layer. In the latter case the layer before foaming can be subjected to packing.

FIELD OF THE INVENTION

The invention relates to the compositions for producing foamedpolyvinylchloride (PVC) materials and to the methods of theirproduction.

It is known, that foamed PVC materials with improved physical andmechanical properties, e.g. high elasticity and thermostability, veryoften are multicomponent systems, including a number of specially aimedadditives: foaming, stabilizing and cross-linking agents, fillers,lubricants, etc.

There is known a six-component composition for producing foamed PVCmaterial (U.S. Pat. No. 4,434,251, C 08 J 9/10, published in 1984),consisting of PVC, plasticizer (dioctylphthalate), stabilizing agent(tribasic and dibasic lead stearate), bubble nucleation agent (calciumcarbonate), cross-linking agent (triallyl isocyanurate), foaming agent(azodicarbonamide).

From this reference there is known the method of foamed materialproduction, comprising mixing of PVC, dioctylphthalate, lead stearate,calcium carbonate, triallyl isocyanurate and azodicarbonamide on therollers, molding the mixture at 150° C. to obtain 1 mm thickness sheetmaterial, its radiation by an electrons effluent of 6 to 10 Mrad and thefollowing heating on wire screen at 220° C. The material producedaccording to this method has the apparent density of 0.10-0.12 g/cu.cm,and the gel content is 28-35%.

There is known a six-component composition for producing foamed PVCmaterial (Japanese Pat. Applic. No. 58-1729, C 08 J 9/06, published in1983), consisting of PVC, plasticizer (esters of phthalic or phosphoricacid), stabilizing agent (organotin derivatives), cross-linking agent(trimethylol propane triacrylate, triallyl isocyanurate), foaming agent(azodicarbonamide), filler (chalk, magnesium oxide, talc).

From this reference there is known the method of foamed materialproduction, comprising mixing of PVC, plasticizer, stabilizing agent,cross-linking agent, foaming agent and filler on the rollers at140°-165° C., molding the mixture at 150° C. to obtain 1 mm thicknesssheet material, its radiation by an electrons effluent of 8 to 10 Mradand the following heating on wire screen by hot air at 220° C. Thematerial produced according to this method has the apparent density ofless than 0.3 g/cu.cm, and the gel content is 20-60%.

The proximate to the composition suggested, according to the technicalconcept, is the known two-component composition for producing foamed PVCmaterial, this composition consists of 100 mass parts of emulsion PVCand 5-30 mass parts of polar organic liquid, in particular, the mixtureof dimethyl formamide with ethylene glycol (GB Patent No. 1549949, C3C,established in 1979).

From this reference there is known the method, which is proximate to themethod of the present invention according to the technical concept. Thisknown method presents the process of foamed PVC material productioncomprising mixing of the powder emulsion PVC with addition of a polarliquid (the mixture of dimethyl formamide and ethylene glycol) in amountof 5-30 mass parts per 100 mass parts of PVC, molding under pressure of1-25 MPa and heating in a high-frequency field at the rate of 190°C./min. for 40 s. The obtained material has the apparent density of0.9-1.0 g/cu.cm, the compressive strength of 8-13 MPa (withoutindication, what deformation limits these values are related to).Reproduction of this method showed, that the material is characterizedby absence of insoluble fraction, at 50% compression deformation thematerial is destroyed; the material destruction rate under vacuum at175° C., which characterizes its thermostability, is 1.25.10⁻⁶ mg HCl/gPVC.s.

DESCRIPTION OF THE INVENTION

An object of this invention is to provide the foamed PVC material withimproved strength and thermostability, produced on the simplecomposition base.

To achieve this object there is suggested the composition for producingthe foamed polyvinylchoride material, consisting of polyvinylchlorideand a polar compound additive, which contains suspension or masspolyvinylchloride, as a polyvinylchloride, and sodium alkyl sulfonate,as an additive, in the following component ratio, mass parts:

    ______________________________________                                        polyvinylchloride 100                                                         sodium alkyl sulfonate                                                                          0.5-5.                                                      ______________________________________                                    

This object is also achieved by simultaneous suggestion of the methodfor the foamed polyvinylchloride material production, which comprisesmixing of powder polyvinylchloride with a polar compound additive,molding of the mixture and the following heating, characterized in thatsuspension or mass polyvinylchloride is mixed with sodium alkylsulfonate, taken in amount of 0.5-5 mass parts per 100 mass parts ofpolyvinylchloride, then it is molded and heated in a free state at190°-300° C. for 3-15 mins.

Production of the two-component composition and its treatment accordingto the suggested method allow to obtain PVC materials with improvedstrength and thermostability: the obtained material has a cellularporous structure, characterized by 0.20-1.0 g/cu.cm apparent density,5-85% cross-linking extent, absence of breaking stress at compression,the relation of compression stress by 50% compression deformation toapparent density being 13.5-52.0 MPa.cu.cm/g and the destruction rateunder vacuum at 175° C. being 0.20-0.80 mg HCl/g PVC.s. From the priorart there are unknown cross-linked foamed PVC materials of cellularstructure, obtained on the two-component composition base.

The sodium alkyl sulfonate use in amount of less than 0.5 mass parts per100 mass parts of PVC does not provide formation of a cross-linkingstructure and, consequently, obtaining of a stable material. Addition tothe composition of more than 5 mass parts of sodium alkyl sulfonate per100 mass parts of PVC worsens foaming of PVC and leads to formation of ahigh apparent density material.

DESCRIPTION OF THE ALTERNATIVE EMBODIMENTS OF THE INVENTION

Depending on what kind of articles are to be manufactured of theproposed composition according to the suggested method, the alternativeembodiments of the composition molding are possible.

If the material is intended for production of piece articles of apredetermined shape, it is advisable to carry out molding of thecomposition under the pressure of 0.5-400 MPa and the temperature of20°-170° C. to achieve 0.72-1.28 g/cu.cm density, followed by heating inthe closed space to 140°-150° C., then the molded composition issubjected to heating for foaming.

Realization of this alternative embodiment of molding under the pressureof above 400 MPa or at the temperature of below 20° C. does not affectthe material properties, but requires substantial power consumption.Under the molding pressure of below 0.5 MPa or at the moldingtemperature of above 170° C., either without heating in the closed spacethere is no formation of the material suitable for application. Moldingof the powder PVC to achieve density of below 0.72 g/cu.cm or above 1.28g/cu.cm, either do, not allow to obtain an integral material, or leadsto obtaining the material, having high apparent density and lowcross-linking extent.

Heating of the molded composition for foaming proceeds at 190°-300° C.for 3-15 mins., and, as a rule, the increase of heating temperaturereduces its required duration. At lesser values of heating temperatureand time a noncross-linked material of high apparent density is formed.The process realization at the heating temperature and time, which areabove the claimed ones, does not lead to formation of porous materialuseful for application.

To obtain the textured surface articles or long-size articles anotheralternative embodiment is preferred, in which the composition is moldedin a free state in the form of 2-16 mm thickness layer, then the moldedcomposition is subjected to heating for foaming.

Molding of the layer of thickness of less than 2 mm leads to formationof the material of high apparent density, as for the layer of thicknessof more than 16 mm it does not allow to produce material suitable forapplication.

The mixture layer after molding can be subjected to packing, e.g. bysqueegeing with a smooth roller, or by any other known method. Itallows, at other parameters being equal, to obtain more light material(in the above mentioned ranges of apparent density).

The molded composition heating for foaming according to this alternativeembodiment proceeds at 220°-300° C. for 3-20 mins. In this case, as wellas in the first embodiment, an inverse ratio of heating temperature totime takes place; the results of heating procedure at the temperatureand the pressure dropped out from the claimed limits are analogous tothat of the first embodiment.

Preference of one of the embodiments for producing certain articles doesnot mean, that these articles cannot be produced according to otherembodiment: and article can be obtained according to any alternativeembodiment.

The material properties, required for a definite user, in the abovementioned ranges are achieved due to the selection of an embodiment andits production parameters in the claimed ranges.

For better understanding of the present invention there are givenillustrative examples of its realization.

EXAMPLE 1

0.5 mass parts of sodium alkyl sulfonate are added to 100 mass parts ofsuspension PVC (GOST 14332-78), the composition is being mixed andmolded at 150 MPa and the temperature of 20° C. to achieve blank density(r_(p)) of 1.25 g/cu.cm, then it is heated in the closed space to thetemperature (T_(hc)) of 140° C., then it is heated in a free state atthe temperature (T_(ho)) of 250° C. for 7 mins. (t_(ho)).

By method of hydrostatic weighing an apparent density of the foamedmaterial (r_(m)) is determined. An insoluble fraction amount (P_(if)) isdetermined by way of solving in tetrahydrofuran for 24 hrs. at 30° C.The compression stress at 50% deformation is determined (GOST 23206-78)and the ratio of this index to the material apparent density P_(c)/r_(m) is calculated. To determine the compression strength appeared tobe impossible because during the compression test according to astandard method the material is strained without breaking. Thethermodestruction rate (V_(HCl)) is determined as the amount of HCl,evolved at 175° C. under vacuum, per unit of PVC mass in a unit of time.

Table 1 illustrates the composition formulation, working conditions andthe material properties according to this and the following examples.

EXAMPLES 2-11

The process is performed according to the procedure of Example 1, thecomposition formulation and the method conditions being changed. Thus,in Examples 2-3 and 5-11 a suspension PVC is used, in example 4 a massPVC (TU 6-01-678-86) is used.

EXAMPLE 12 (comparative, according to the GB Patent No. 1549949).

100 mass parts of emulsion PVC, 10 mass parts of dimethyl formamide, 10mass parts of ethylene glycol are mixed for 0.5 hr in a mixer, thecomposition is molded under the pressure of 1.5 MPa for 3 mins. intopellets with diameter of 100 mm and thickness of 30 mm. The thermaltreatment is carried out in a high-frequency field for 40 s. at a rateof 190° C./min., and the properties are determined.

EXAMPLE 13

100 mass parts of powder suspension PVC (GOST 14332-78) are mixed with0.5 mass parts of sodium alkyl sulfonate, filled to form layer of 6 mmthickness and heated at the temperature in the oven of 250° C. for 12mins. The foamed PVC material is obtained, and its properties aredetermined according to Example 1.

Table 2 illustrates the composition formulation, working conditions andthe material properties according to this and the following examples.

EXAMPLES 14-27

The process is performed according to the procedure of Example 13, thecomposition formulation and the method conditions being changed, thus,in Examples 14-20 a suspension PVC (GOST 14332-78) is used, in Example21-27 a mass PVC (TU 6-01-678-86) is used.

EXAMPLE 28

The process is performed according to the procedure of Example 14, thecomposition layer is being molded on a metal band by a smooth roller.

EXAMPLE 29

The process is performed according to the procedure of Example 22, thecomposition layer is being molded on a metal band by a smooth roller.

COMMERCIAL APPLICABILITY

The compositions according to the invention may be produced oncommercial scale and processed according to the method of the presentinvention into the foamed materials, which can be used as heatshielding, and vibration-, sound- and acoustic-proofing materials,applied in automotive industry, ship-building industry, aircraftindustry etc., as well as in production of various household articles.

                                      TABLE 1                                     __________________________________________________________________________    Foamed PVC material production conditions and properties                      Amount                                                                        of sodium                                                                     alkyl sul-                                                                    fonate,                                                                       mass parts                       Properties of the material                   per 100   Molding conditions                                                                          Heating conditions    V.sub.HCl                       No. of ex.                                                                         mass parts of PVC                                                                  Pressure MPa                                                                      Temperature °C.                                                              r.sub.p  g/cu.cm                                                                  T.sub.hc  °C.                                                             T.sub.ho  °C.                                                             t.sub.ho  min                                                                    r.sub.m  g/cu.cm                                                                  P.sub.if  %                                                                      P.sub.c /r.sub.m  MPa.cu.cm/g                                                        ##STR1##                       1    2    3   4     5   6  7  8  9   10 11    12                              __________________________________________________________________________    1.   0.5  150  20   1.25                                                                              140                                                                              250                                                                               7 0.38                                                                              31 14.3  0.50                            2.   2.5  150  20   1.25                                                                              140                                                                              250                                                                               7 0.39                                                                              48 15.2  0.50                            3.   5    150  20   1.25                                                                              140                                                                              250                                                                               7 0.40                                                                              71 18.0  0.50                            4.   2.5  150  20   1.28                                                                              140                                                                              250                                                                               8 0.20                                                                              54 13.5  0.70                            5.   5     0.5                                                                               80   0.72                                                                              140                                                                              240                                                                               7 0.53                                                                              36 23.8  0.40                            6.   5    400  20   1.25                                                                              140                                                                              250                                                                               7.5                                                                             0.30                                                                              80 13.8  0.50                            7.   5     0.5                                                                              170   1.21                                                                              140                                                                              250                                                                               6 0.41                                                                              41 22.3  0.40                            8.   5    150  20   1.25                                                                              150                                                                              250                                                                               6 0.35                                                                              48 20.4  0.50                            9.   5     50 100   1.25                                                                              140                                                                              190                                                                              15 0.62                                                                              26 47.1  0.45                            0.   5     50  90   1.23                                                                              140                                                                              300                                                                               3 0.38                                                                              37 13.9  0.50                            1.   5     2   80   1.20                                                                              145                                                                              200                                                                               7 1.00                                                                              20 52.0  0.20                            2.   --    1.5                                                                               20   0.98                                                                              -- 135                                                                               0.7                                                                             0.9-1.0                                                                            0 destroyed                                                                           1.25                            compar.)                                                                      __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________    Foamed PVC material production conditions and properties                      Amount                                                                        of sodium                                                                     alkyl sul-                                                                    fonate,                                                                       mass parts                                                                              Heating                                                                              Properties of the material                                   per 100                                                                            Thickness                                                                          conditions           V.sub.HCl                                      mass parts of PVC                                                                  of layer, mm                                                                       T.sub.h  °C.                                                               t.sub.h  min.                                                                    r.sub.m  g/cu.cm                                                                  P.sub.if  %                                                                       P.sub.c /r.sub.m  MPa.cu.cm/g                                                        ##STR2##                                      __________________________________________________________________________    0.5   6   250 12 0.30                                                                              48  13.2  0.50                                           1.5   4   250 11 0.36                                                                              42  16.2  0.50                                           5     4   250 15 0.24                                                                              85  13.4  0.55                                           1.5   2   250  4 0.49                                                                              18  14.8  0.40                                           1.5   8   250 16 0.20                                                                              84  13.5  0.80                                           1.5  16   250 18 0.28                                                                              70  13.9  0.50                                           1.5   2   220 20 0.97                                                                               5  31.0  0.20                                           0.5   2   300  3 1.00                                                                               5  32.0  0.20                                           0.5   7   250 13 0.31                                                                              48  14.6  0.50                                           1.5   5   250 12 0.35                                                                              42  17.1  0.50                                           5     5   250 10 0.75                                                                              13  24.3  0.20                                           1.5   2   250  5 0.50                                                                              18  18.7  0.40                                           1.5  16   250 17 0.22                                                                              76  13.5  0.75                                           1.5   2   220 20 0.96                                                                               5  29.4  0.20                                           1.5   3   300  3 1.00                                                                               5  31.6  0.20                                           1.5   4   250 11 0.25                                                                              78  16.2  0.70                                           1.5   5   250 12 0.24                                                                              77  17.2  0.70                                           __________________________________________________________________________

We claim:
 1. A process for the foamed polyvinylchloride production,which comprises mixing of powder polyvinylchloride with a polar compoundadditive, molding of the mixture and the following heating,characterized in that suspension or mass polyvinylchloride is mixed withsodium alkyl sulfonate, taken in amount of 0.5-5 mass parts per 100 massparts of polyvinylchloride, is molded and is heated in a free state at190°-300° C. for 3-20 mins.
 2. A process as claimed in claim 1,characterized in that the composition is molded under the pressure of0.5-400 MPa and the temperature of 20°-170° C. to achieve density of0.72-1.28 g/cu.cm, and before heating in a free state it is heated inthe closed space to 140°-150° C.
 3. A process as claimed in claim 1,characterized in that the composition is molded in a free state in theform of 2-16 mm thickness layer.
 4. A process as claimed in claim 3,characterized in that the layer of the mixture after its formation isbeing packed.